In an energy driven life scenario and rising environmental crisis, development of suitable (environmental friendly and cost effective) methods to generate and store energy has become a priority. There are number of conventional methods (nuclear, thermal, hydro etc.) to generate and store energy (flywheels, batteries, compressed air, thermal storage etc.) but with a shift towards non-conventional and renewable energy sources which are time and climate condition specific, there is a dire need to be able to store energy generated at any time for its use at any other desired time. Presently, the capacitor is considered as a best energy storage device but has been limited with its capacity which depend on its (capacitor) size parameters. Scientists are always looking towards developing super capacitors with a large capacity to store energy for its desired use. A supercapacitor in comparison to the ordinary capacitor has much higher capacity and energy density as well as higher power density. Supercapictors excel in charging time taking only from 1 to 10 seconds, compared to 10 to 60 minutes to reach a full charge on a battery. The charging life of typical batteries is 500-1000 charge-discharge cycles while supercapacitors can reach up to one million cycles. Thus, supercapacitors are of interest because, unlike batteries, they can deliver blindingly fast bursts of power and they recharge quickly.
Instead of designing supercapacitors with traditional materials and the using them for energy storage, scientists are working on to convert materials to be used in construction of houses like bricks to act as supercapacitors and become a source of continuous energy supply to the place. To make use of renewable energy sources like solar and wind, more useful sources of energy, the solar panels and wind turbines are multiplying and the big problem is how to store all the excess electricity produced when the sun is up or the wind blowing so it can be used at other times. Potential solutions have been suggested in many forms, including massive battery banks, fast-spinning flywheels, and underground vaults of air. In comparison to mass and energy density ratio, supercapacitors though store relatively little energy compared to batteries. In an electric vehicle, a supercapacitor supports acceleration, but the lithium-ion module is what provides power for hundreds of miles. Yet many scientists and technology developers are hoping supercapacitors can replace conventional batteries in many applications, owing to the steep environmental toll of mining and disposing of metals required to fabricate batteries.
Bricks are always known to become hot when exposed to heat but a team of researchers now say that this classic construction material (the red fired brick) could be a contender in the quest for energy storage. The common brick is porous and it’s red color comes from pigmentation that is rich in iron oxide. These both features (porous and iron oxide) provide ideal conditions for growing and hosting conductive polymers and a research team at Washington University in St. Louis (USA) has been able to transform these basic building blocks (bricks) into supercapacitors that can illuminate a light-emitting diode. The building brick proof-of-concept project presents new possibilities for the world’s many brick walls and structures to be self-made power houses with unlimited power supply. According to the scientists, a brick supercapacitor coated with a simple five-minute epoxy is immersed in water, demonstrating the device’s impermeability. According to scientists responsible for the project, rooftop solar panels connected by wires could charge the bricks, which in turn could provide in-house backup power for emergency lighting or other applications. With the success of the project, there will no need of any type of batteries in the houses as the bricks of the house themselves would be the batteries. Though, the novel device is a far cry from the megawatt-scale storage projects related to renewable (solar) energy which are underway all over the world but it is demonstrated for the first time that bricks can store electrical energy and can offer “food for thought” in a sector that’s searching for ideas.
At present level of the project, if applied to 50 bricks, the supercapacitor could power 3 watts’ worth of lights for about 50 minutes. The current set-up can be recharged 10,000 times and still retain about 90 percent of its original capacitance. Researchers are developing the polymer’s chemistry further in an effort to reach 100,000 recharges. However, to really make inroads into the dominance of batteries, where a chemical reaction drives creation of a voltage, supercapacitors will need to significantly increase their energy density. At present, according to researchers, electrically charged bricks are “two orders of magnitude away” from lithium-ion batteries, in terms of the amount of energy they can store and they are trying to make polymers which can store more energy.
The St. Louis researchers are not alone in the quest to use every day materials to make supercapacitors. In Scotland, a team at the University of Glasgow has also developed a flexible device that can be fully charged with human sweat. Researchers applied a thin layer of PEDOT to a piece of polyester cellulose cloth that absorbs the wearer’s perspiration, creating an electrochemical reaction and generating electricity. The idea is that these coated cloths could power wearable electronics, using a tiny amount of sweat to keep running. The Indian Institute of Technology-Hyderabad is exploring the use of corn husks in high-voltage supercapacitors. India’s corn producing states generate substantial amounts of husk waste, which researchers say can be converted into activated carbon electrodes. The biomass offers a potentially cheaper and simpler alternative to electrodes derived from polymers and similar materials.
Further reading:
- Maria Gallucci, Turning bricks into supercapacitors (13 Aug 2020), IEEE Spectrum magazine. Avaialble at: https://spectrum.ieee.org/energywise/energy/batteries-storage/turning-red-bricks-into-energy-storage-devices
